We had a in ground pebble tec pool put in about 8 yrs ago over the last couple of years the water line around the pool has turned black. In the beginning we thought it might be black algae but we have tried everything we have come across and cant seem to remove it. We have not found anyone who can tell us what it is and with all of the scrubbing and rubbing on the pebble tec it is starting erode the finish. Can anyone shed any light on this problem for us:?:

granny77 wrote:We had a in ground pebble tec pool put in about 8 yrs ago over the last couple of years the water line around the pool has turned black. In the beginning we thought it might be black algae but we have tried everything we have come across and cant seem to remove it. We have not found anyone who can tell us what it is and with all of the scrubbing and rubbing on the pebble tec it is starting erode the finish. Can anyone shed any light on this problem for us:?:

I agree check for metals and another question I might ask is what are your alkanity readings and have you been dumping more than 10 pounds of sodium bicarbonate in at one time?

Had the same problem. There is an easy fix. Get a chlorene tablet and use it like a piece of chalk. Rub it on the black streak, putting it on fairly thick. Leave it overnight.....should be clean the next morning! Worked for me. Good Luck.